Bypass of replication-blocking lesions by DNA translesion (TLS) polymerases is a fundamental biological mechanism for of dealing with potentially lethal DNA damage. Conserved throughout all domains of life, the TLS polymerase DinB has been most extensively characterized in the prokaryote Escherichia coli. Much less is understood about its DinB counterpart, Pol kappa, in eukaryotes. I propose to use the DinB ortholog from the fission yeast Schizosaccharomyces pombe as a model to understand the biochemistry and regulatory mechanisms of DinB in higher eukaryotes. I have set for three specific aims to address these problems: 1) biochemically characterize the translesion bypass capabilities of S. pombe DinB, 2) screen for novel interacting partners that contribute to its regulation, and 3) examine the biochemical and biological significance of the identified protein:protein interactions. [unreadable] [unreadable] [unreadable]